The present invention relates to an apparatus for the wire-stapling of multiple-sheet printed products having a wire section dispenser that includes a wire guide for a continuous stapling wire and a cutting element that cuts the continuous staple wire into staple sized wire sections.
A stapling device of this general type is shown in U.S. Pat. No. 3,762,622. This prior art patent discloses a wire-section dispenser with a wire guide for a stapling wire which is to be advanced in a stepwise manner. There is a cutting element, downstream of the wire guide, along the advancement direction of the stapling wire, which is in the form of a lever. The lever is rotatably driven about an axis that is parallel to the advancement direction of the stapling wire, and has, at its radial end, carry-along teeth which contact the advanced initial region of the stapling wire. There is interaction with a fixed cutter, that severs a wire section from the continuous stapling wire. The wire section is arranged between the radial end of the cutting element and a quarter-circle guide element, and is carried through approximately 90.degree. by the carry-along teeth and is fed to a retaining device. The retaining device has a gap which is bounded by a first retaining element, in the form of a leaf spring, and a stationary second retaining element, in the form of a block, which is adjacent and tangent to rotational path of the carry-along teeth. The retainer moves, along its longitudinal extent, at right angles with respect to the wire section. The wire section is guided into the retainer device, and slide off the carry-along teeth in the process. The wire section is retained under the spring action of the first retaining element. A rotating stapling head has a carry-along member including a carry-along flank which, upon passing the gap, comes into contact with the wire section and delivers the wire section out of the gap. The gap is open downstream, as seen in the movement direction of the carry-along member. A wheel-like rotary bending element is provided downstream of the gap, which is intended to force the wire section carried by the carry-along member into a staple guide of the stapling head. The wire section is simultaneously being formed into a staple. The staple is retained in the staple guide and its legs are then forced out and pushed, through a plurality of paper webs located one upon the other. The legs of the staple are then bent over. In this prior art apparatus, there are jolts of considerable magnitude each time the rotating cutting element comes into contact with the stapling wire. This presents a problem to acceptable operation of this prior art apparatus since the wire section must be accelerated at the same time as the wire is being cut. Also for these reasons the prior art apparatus has a non-smooth operation, it requires a considerable amount of space and it can only process staple wires having a limited selection of diameters.
Another prior art wire-stapling apparatus for multiple-sheet printed products is disclosed in U.S. Pat. No. 4,750,661 and the corresponding European Patent Application EP-A-0205144. This prior art apparatus uses a rotating carrying mechanism, having crossed arms. Stapling heads are mounted at the free ends of the arms and move past a wire guide as the carrying mechanism rotates. Stapling wire is advanced in a stepwise manner through the wire guide and as each. stapling head moves runs past the wire guide, one wire section is severed from the stapling wire by a cutting element arranged on the stapling head. A carry-along member, that is a part of the stapling head, carries the wire section. The wire section is then forced, by a rotatably mounted wheel-like bending element, into a staple guide of the stapling head. The wire section is simultaneously bent to form a staple. When the cutting element contacts the stapling wire, the stapling head is subjected to a considerable jolt, which, in addition to the high stress load that is placed on the mechanism also causes a non-smooth operation.
Therefore it is an object of the present invention to provide an apparatus of the general type that is more compact such that it has a space-saving simple construction and ensures smooth operation.